It is known to use outlet elements having a lateral outlet aperture for feeding melts in the production of continuous steel castings having an elongated rectangular form (Slabs). Usually, outlet elements of this kind are used in order on the one hand to improve the surface quality of the casting produced, and on the other hand to influence advantageously in addition the flow conditions of the steel flowing into the mould, in order to improve the degree of purity in the castings which are produced.